Al Qaeda-linked terrorists have transformed a government-run school in the restive tribal region of Pakistan into a nursery for suicide bombers, training children as young as nine.

"It was like a factory that had been recruiting nine to 12-year-old boys and turning them into suicide bombers," Maj Gen Tariq Khan, the commander of the division that captured the area, was quoted in The Daily Telegraph as saying on Tuesday.

The camp was located in a territory in South Waziristan where the notorious Pakistani Taliban commander, Baitullah Mehsud, operates.

At another location, military investigators found film footage on a DVD that they believed depicts children at the school being trained in suicide bombing.

The footage, shown to journalists, contained images of a masked teacher instructing rows of school children who wore white headbands inscribed with Quranic verses.

Maj Gen Athar Abbas, the army's chief spokesman, said the school and a hospital had been taken over by terrorists "to prepare children for suicide attacks and for making improvised explosive devices."

During operations in the area, the soldiers had rounded up over 50 boys who were undergoing suicide attack training, the report said. Many of the boys had been kidnapped.

Most of them were from the ethnic Pushtun belt of the North West Frontier Province and some were locals from South Waziristan.

"The boys were handed to an NGO to be looked at," Maj Gen Abbas said.

He said in the operation in January, the army found jackets and ball bearings which are used in suicide attacks.

Since January last year, Pakistan has witnessed over 80 suicide attacks that have killed more than 1,000 people.

Many of the suicide attacks in neighbouring Afghanistan -- some reported to have involved teenagers and even younger children -- have also originated on the Pakistani side of the border, the report said.